If you feel like it’s been a long day, you’re not just imagining things.
The world is bracing for a “leap second” tonight, where clocks will be adjusted by exactly one second to sync up more closely with the Earth’s rotation around the Sun. The reason we need to do this is because of the system humans rely on to measure time, called Coordinated Universal Time (UTC). It’s the measurement that stipulates that there are 60 seconds in a minute, or 86,400 seconds in a day. The problem with that approach, however, is that the Earth’s rotation is gradually slowing, meaning an average day is now about two milliseconds longer than UTC allows. If scientists didn’t add these seconds to the clock on a regular basis, our timekeepers would gradually begin to get thrown out of sync and, eventually, sunsets would be taking place at 6 a.m.
This practice only began in 1972, after scientists began noticing the discrepancy. Since then, there have been approximately 25 leap seconds added to the clock, with the most recent one occurring on June 30, 2012. Tonight, right at the stroke of midnight, some clocks will actually read “23:59:60” instead of the normal “23:59:59”. But due to various time zones, the change will actually occur at 7:59 p.m. for those living in Eastern Time Zone.
The leap second doesn’t come without its fair share of controversy though.
The United States’ official global position system committee actually went as far to declare leap seconds as hazard to technology last year. Just like with Y2K back in 2000, the committee argues clocks and mapping systems aren’t built to handle the formatting of an extra second. But physics and astronomy lecturer Rob Cockroft says those concerns are being blown out of proportion.
“It might cause minor problems, nothing we have to worry about crazily,” he says in the video above. “There are some disruptions but nothing major.”
So the real question is: What are going going to do with your extra second tonight? Check out the video above.